Aqueous solution of lactoflavin



UNITED STATES PATENTOOFFICE AQUEOUS SOLUTION OF LACI'OFLAVIN Ernst Preiswerk, Mnnchenstcln, near Basel, Switzerland, assignor to Hoihnann-La Roche v Ina, Nutley, N. 1., a corporation of New Jersey No Drawing. Application April 9, 1042, Serial No.

438,325. In Switaerland April 8, 1941 6 Claims. (CL 167-81) In order to prepare aqueous solutions of lactoilavin (vitamin B2) in appropriate concentrations for use in therapy, the employment of materials for increasing the solubility is necessary.

hydroxy-benzoic acid and of its monoalkyl-ether with alkalis or strong organic bases lies between 5 and 6, within which range lactoflavin is stable.

Solutions of the water-soluble salts of 2,4-dihydroxy-benzoic acid and of its monoalkyl-ether with alkalis or strong organic bases, as such or mixed with each other or with other materials known to increase solubility or known as bufler substances, are therefore to be used as solubilis-.

ing agents.

Example 1 5.5 parts by weight of the sodium salt-oi 2,4-

dihydroxy-benzoic acid are dissolved in 100 parts by weight of water and this solution shaken with But very few physiologically indiii'erent materit 05 part by weight of lactoflavm at room temper 818 have hitherto become known which, 88 such ature until it is completely dissolved.

or in aqueous solution, are capable of increasing the solubility of lactoflavin, However, with these Example 2 compounds, as evidenced for instance by German 24.07 parts by weight of 2,4-dihydroxy-benzoic patent specification No. 688,047, only a moderate acid are neutralised with 1 part by weight of increase in the solubility of lactoflavin can be oblithium-carbonate, and water added to give a voltained, via: from 0.013% to 0.4% at the highest, ume of 100 parts. 3 parts by weight 01! lactoflavin and comparatively large quantities 01' said soluare added to the filtered solution, the pH of bilising agents are necessary. which should be 5.2. The lactoflavin dissolves on It has now been found that the aqueous soluh kin 01' i rin Witho ext rn l he tin in tions of salts of 2,4-dihydroxy-benzolc acid, or of a few minutes, renderin a mpl t y 1 its monoalkyl-ether, with alkalis, such as light lution.

metals and ammonia, or strong organic bases, rl 3 possess a strongly marked dissolving powder for 10 parts by weight f the sodium salt f lactoilavin; there may be used water-soluble ordroxy 4 ethoxy benmic acid are dissolved m 100 831110 bases higher P than 9, which are Physiparts by weight of water and this solution shaken ologically indifierent, e. g., lower primary, secwith L8 parts by weight f la toflavin at room ondary or tertiary alkylamines, primary aralkyltemperature until t; has dissolved,

amines, hydroaromatic amines, such as cyclohexl 4 ylamine, and saturated heterocyclic compounds, Exam? 8 such as morpholine and piperidine. Thus, a 6% 25 parts by weight of the sodium salt of z-hysolution of the sodium salt of 2,4-dihydroxydroxy-4-methoxy-benzoic acid and 3 parts by benzoic acid is capable of dissolving about 0.5% weight of lactoflavin are shaken with 72 parts of lactoflavin, a 25% solution of lithium salt more by weight of water until a clear solution is obthan 3% of lactoflavin. With a 10% solution of tained.

the sodium salt 01' 2-hydroxy-4-ethoxy-benzoic Example 5 acid up to 1.8% of lactoflavin can be kept in sowith 8.25% solution Of the sodium Salt Of 2-hyas crystals f melting 12 2 o C.) and 1 part droxy-i-methoxy-benzoic acid. By means of the I by weight or lactoflavm are shaken with 90 parts salts of organic bases aqueous solutions having a by weight of water, whereby a clear solution is lactoflavin content of up to 4% can be prepared. obtained m a few minutes which contains 1% of The water-soluble salts of dihydroxy-benzoic lactoflavlm acid and of its monoalkyl-ether with alkalis or Example 6 strong organic bases are not toxic and are well tolerated. Thus, for instance, a rabbit shows no 10 parts by weight of 24'dmydmxy'benzoic symptoms whatever oi any toxic reaction on inacid are suspended in 40 parts by weight or travenous administration of 1.5 grams per kiloter and neutralized by the addition or parts gram. The pH of the water-soluble salts 01' diby weight aquem methylamine or of the equivalent quantity of dimethylamine of any other concentration, and brought to 63 parts by volume, whereby a 20% solution of the dimethylamine salt of 2,4-dihydroxy-benzoic 5 acid results.

In this solution up to 3.4% of lactoflavin can easily be dissolved.

Example 7 10 parts by weight of 2,4-dihydroxy-benzoic as acid are neutralised with 20.1 parts by weight of a aqueous solution of methylamine, 2.4 parts by weight of lactoflavin added, which dissolves completely in a few minutes. The whole is then diluted with water to 60 parts by volume. A solution of the methylamine salt 0! 2,4-dihydroxy-benzoic acid is thereby obtained, which contains 4% of lactoflavin'.

Example 8 parts by weight of the diethylamino ethanol salt of 2,4-dihydroxy-benzoic' acid (melting point -91 C.) aredissolved in water to a volume 0! parts and 2 parts by weight of lactoflavin dissolved therein by shaking. This solution contains 40% of the diethylamino-ethanol salt of 2,4-dihydroxy-benzoic acid and 2% of lactoflavin.

Example 10 15.4 parts by weight of 2-hydroxy-4-methoxybenzoic acid are dissolved in 48 parts by weight so oi a 20% aqueous solution 0! dfethsncl-amine. i part by weight of lactoflavin is then added and the whole diluted to 100 parts by volume with water.

The resulting solution which is almost neutral contains 1% o! lactoiiavin.

I claim:

1. An aqueous solution 0! more than .013% of lactoflavin containing a water-soluble salt of a compound selected from the group consisting of 2,4-dihydroxy-benzoic acid and its mono-alkyl ethers.

2. Aqueous solutions of more than .013% oi lactoflavin containing a salt of dihydroxy-benzoic acid with a physiologically indiflerent water-soluble organic base.

3. Aqueous solutions of more than .013% lactonavin containing dihydroxy-benmic acid methylamine salt.

4. Aqueous solutions of more than .013% of lactoflavln containing a salt of 2-hydroxy-4-alkoxy-benzolc acid with an alkali metal.

5. Aqueous solutions of more than .0i3% oi lactoflavln containing 2 hydroxy 4 methoxybenzoic acid sodium salt.

6. Aqueous solutions of more than .013% oi lactoilavin wntainins 2-hydtoXy-4-ethoxy-benzolc acid sodium salt.

ERNST PREISWERK. 

